Automatic test equipment (ATE) refers to an automated, usually computer-driven, approach to testing devices, such as semiconductors, electronic circuits, and printed circuit board assemblies. ATE typically includes at least two basic transmission paths: a source path and a capture path. The source path is used to transmit signals to a device under test (DUT), and the capture path is used to obtain signals from the DUT.
The source path and the capture path both include transmission media, over which source and capture signals pass. Differences in mechanical and electrical properties of the transmission media, however slight, can affect the source and capture signals. For example, the transmission media may cause unintended phase delays in signals in both the source path and the capture path. Similarly, the transmission media can affect the amplitudes of such signals. Typically, amplitude losses result during transmission, however, unintended amplitude gains may also result. In ATE parlance, amplitude gains and losses are both referred to as “gains”—since a loss in amplitude is the equivalent of a negative gain.
Phase delays and amplitude gains in the source path and capture path can have a negative effect on the accuracy of the ATE.